Possible mistakes

Vehicles spawn on top of each other

This is because the vehicles you are trying to spawn take a long time to load. To fix this you have two options: 1- Optimize the vehicles (recommended) 2- Edit the delcar() function in line 94 of config.lua:

function delcar()
    local vehicle = nil
    while vehicle ~= 0 do
        local vehicle = GetClosestVehicle(GetEntityCoords(PlayerPedId()), 50.0, 0, 70)
        DeleteEntity(vehicle)
        if vehicle == 0 then
            vehicle = nil
            break
        end
    end
end